1. Field of the Invention
This invention pertains to the art of rotary or dynamic seals particularly useful in the field of centrifugal refrigerant gas compressors.
2. Description of the Prior Art
U.S. patents of which applicant is aware and which have some similarities with respect to seals and/or venting passages are: U.S. Pat. No. 838,744; U.S. Pat. No. 3,392,910; U.S. Pt. No. 3,480,284; U.S. Pat. No. 3,493,169; U.S. Pat. No. 3,647,313. It is applicant's view that the teachings in these patents do not anticipate or make obvious the invention claimed herein.
From the standpoint of structural similarities of certain of the parts, the closest prior art which applicant is aware is the centrifugal refrigerant compressor units currently produced by applicant's assignee. These devices provide an environment in which applicant's invention finds one of its most useful applications. The general arrangement of the centrifugal compressor impeller and shaft assembly and the assembly including the driving motor, sump chamber in which the drive train connecting the motor to the impeller is located and the general casing arrangement, are shown in U.S. Pat. Nos. 3,601,501 and 3,619,086, to which reference should be had for a full understanding of one general construction of a centrifugal refrigerant compressor in which the present invention is incorporated.
The present seal between the high pressure discharge space and the sump chamber on the opposite side of the wall separating these spaces is provided by a seal rotor and seal stator providing an ordinary serrated bushing type seal. The leakage of refrigerant gas from the high pressure discharge chamber side through such a seal to the sump chamber, which is maintained at substantially the same pressure as the suction pressure to the compressor inlet by venting the sump chamber to the inlet side of the impeller through an oil-refrigerant separator and oil filter arrangement, is sufficiently high with the relatively small volume sump chamber used on the relatively compact centrifugal compressor assembly, that periodically the system must be shut down to permit oil which has accumulated in the oil filter accumulator to be returned to the sump chamber. The excessive rate of refrigerant gas leakage from the high pressure side to the sump chamber creates the problem which this invention is intended to solve. A further explanation of the arrangement as a whole and the advantages accruing from the improved seal arrangement according to this invention will be set forth hereinafter.